Here is the full list of all 25 Royal Heroes achievements.
Discover all air spells
Discover all water spells
Sacrifice a weak one to make your army stronger
Find and kill all of famous vampires
Find and 'pet' at least 10 sheep
Do something useful. DOIT!
Hire a 4 star hero
Flawless victory - no casualties
Dont be a Batman - do it!
You can't be a winner all the time
Discover all fire spells
Discover all earth spells
Discover all void spells
Warp a few times
Find and restore a famous weapon. Get Warping Power increase.
Veni Vidi Vici!
Clear a whole other dimension. Get Warping Power increase.
Collect the whole set
Craft a weapon that only the worthy can wield
Come to dark side. We have cookies. And extra spell slot.